The present invention relates to signal processing and more particularly to signal processing of amplitude-modulated broadband noise signals.
In the detection and identification of selected modulated broadband noise signals, such as those generated by underwater driven equipment, it is desirable to have a quantitative measurement of the level of modulation. This allows for the immediate reaction to searching for and identifying the sources of the broadband noise supporting the modulation. Demodulation systems of this type presently in use do not have the sensitivity for short time samples to indicate the presence of the desired signal. Neither do they provide the actual amplitude of the modulating signal. Usually the frequency of the modulation line is a darkened trace on continuously moving paper and the level of modulation is a function of the darkness of the line trace. The time to develop the trace requires several minutes.